Organ walls are composed of several layers: the mucosa (the surface layer), the submucosa, the muscularis (muscle layer), and the serosa. In gastrointestinal, colonic, and esophageal cancer, for example, small polyps or cancerous masses may form along the mucosa and often extend into the lumens of the organs. Conventionally, that condition is treated by cutting out a portion of the affected organ wall. This procedure, however, may cause extensive discomfort to patients, and poses health risks. Recently, physicians have adopted a minimally invasive technique called endoscopic mucosal resection (EMR), which removes targeted tissue, such as, e.g., the cancerous or abnormal tissues (polyps), while keeping the organ walls intact.
EMR may be performed with a suitable introduction sheath or an endoscope, which may be a long, narrow elongate member equipped with a light, video camera, and other instruments. During EMR, the endoscope may be passed down the throat or guided through the rectum, for example, to reach the target tissue. For certain procedures, a cutting device, such as a snare or wire loop, may be advanced through a endoscopic channel toward the target tissue. Once the cutting device is disposed adjacent the targeted tissue, the targeted tissue may be pulled towards the cutting device by, e.g., a vacuum suction, and the cutting device may resect the targeted tissue from surrounding tissue. Subsequently, the excised tissue may be extracted for examination, biopsy, or disposal.
In some cases, the tissue targeted for removal may be a polyp. Certain polyps, such as pedunculated polyps, are characterized by a stalk attached to the mucosal layer. Drawing such polyps into the cap without drawing in any other tissue is readily accomplished. Other polyps, such as sessile polyps, however, exhibit a broad base and they lay flat on the mucosal surface, devoid of a stalk. It is often difficult to grasp these polyps without drawing in a part of the muscularis layer.
The thickness of tissue varies at different locations within the body, and therefore, resecting appropriate depth of tissue is critical. EMR, as performed with conventional devices and methods, may resect excessive tissue, resulting in complications such as perforation, bleeding, and/or strictures. In some situations, the entire undesired tissue may not be removed. This situation may require additional procedures or result in the development of metastatic cancer, if the tissue left behind is diseased.
Therefore, there exists a need for an improved endoscopic mucosal resection tool that effectively resects undesired tissue from the body.